RESGPSLNS_JD136.SHP: Ship Trackline along which Continuous Resistivity Profile Data were Collected in the Corsica River Estuary, Maryland on May 16, 2007 on USGS Cruise 07005

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Frequently-anticipated questions:

What does this data set describe?

Title:
RESGPSLNS_JD136.SHP: Ship Trackline along which Continuous Resistivity Profile Data were Collected in the Corsica River Estuary, Maryland on May 16, 2007 on USGS Cruise 07005
Abstract:
Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine the importance of nutrient delivery to Chesapeake Bay via this pathway. Resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge from this primarily agricultural watershed that may be contributing to eutrophication, harmful algal blooms, and fish kills. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the estuary in April and May 2007. Techniques used included continuous resistivity profiling (CRP), piezometer sampling, seepage meter measurements, and collection of a radon tracer time series. Better understanding of the style, locations, and rates of groundwater discharge could lead to improved models and mitigation strategies for estuarine nutrient over-enrichment in the Corsica River Estuary, and other similar settings. More information on the field work can be accessed from the Woods Hole Coastal and Marine Science Center Field Activity webpage: <http://quashnet.er.usgs.gov/data/2007/07005/>
  1. How should this data set be cited?

    Bratton, John F. , and Cross, VeeAnn A. , 2011, RESGPSLNS_JD136.SHP: Ship Trackline along which Continuous Resistivity Profile Data were Collected in the Corsica River Estuary, Maryland on May 16, 2007 on USGS Cruise 07005: Open-File Report 2010-1094, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A. , Bratton, John F. , Worley, Charles R. , Crusius, John, and Kroeger, Kevin D. , 2011, Continuous resistivity profiling data from the Corsica River Estuary, Maryland: Open-File Report 2010-1094, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -76.149983
    East_Bounding_Coordinate: -76.106650
    North_Bounding_Coordinate: 39.087067
    South_Bounding_Coordinate: 39.074133

  3. What does it look like?

    <https://pubs.usgs.gov/of/2010/1094/data/navigation/resgpslns_jd136.gif> (GIF)
    Thumbnail image showing the location of resistivity tracklines collected May 16, 2007. The coastline is included for spatial reference.

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 16-May-2007
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • String (25)

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Explicit depth coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    resgpslns_jd136
    ESRI polyline shapefile (Source: ESRI)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    Id
    An automatically generated numeric value. (Source: VACExtras v2.1)

    Range of values
    Minimum:0
    Maximum:0

    line
    The alphanumeric name corresponding to the prefix of the GPS filename. This name reflects the name assigned to the line of data acquisition and incorporates modifiers to reflect modification of the GPS file if the GPS file was split into more than one part. (Source: U.S. Geological Survey)

    Character set.

    gpstime
    GPS time in the format HHMMSS. GPS time is +4 from local time during the survey. (Source: U.S. Geological Survey)

    Although the value is represented as a number, the number as a whole doesn't have a particular meaning. Only when the individual parts for hours, minutes, and seconds are broken out does the number have meaning.

    depth_m
    First occurence of the depth of the water below the fathometer in meters recorded by the ship's fathometer/navigation system. Datum is local surface (no tides taken into account). A value of -9999 indicates no data. (Source: U.S. Geological Survey)

    Range of values
    Minimum:0.4
    Maximum:2.9
    Units:meters

    jday
    This number represents the Julian day of data collection based on the GPS day. Julian day is the integer number representing the interval of time in days since January 1 of the year. (Source: U.S. Geological Survey)

    Range of values
    Minimum:136
    Maximum:136
    Units:days

    gpsdate
    The date recorded in the GPS navigation in the format DDMMYY. Because of the time offset from local time, this date could actually be different than the local acquisition date. (Source: U.S. Geological Survey)

    Character set.

    len_utm18
    The length of the polyline in meters (based on UTM, Zone 18, NAD83 projection). (Source: Calculated by XToolsPro version 5.2.)

    Range of values
    Minimum:110.710733
    Maximum:3942.922297
    Units:meters

    hotlink
    Text field which provides the partial path and full filename of the MATLAB JPEG image of the CRP line associated with the trackline. (Source: Data processor.)

    Character set.

    hlink2
    Text field which provides the partial path and full filename of the long JPEG image of the CRP line associated with the trackline. (Source: Data processor.)

    Character set.

    Entity_and_Attribute_Overview:
    In order to effectively utilize the "hotlink" or "hlink2" attribute in ArcGIS, the user must follow a couple of steps. First, the user must open the Layer Properties of the shapefile within ArcMap - select the Display tab - and click on the check box next to "Support Hyperlinks using field:" and the field selected from the dropdown menu needs to be "hotlink" or "hlink2". The hyperlink is set to a document. Additionally, a hyperlink base must be supplied in the ArcMap document (mxd) to complete the full path to the images. This is accomplished from File - Document Properties. On the Summary tab there is a section for "Hyperlink base". The text supplied here needs to be the disk information preceding "data" in the full path to the image. If the data are being read from a DVD, this would be the drive letter such as F:\.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    John F. Bratton
    U.S. Geological Survey
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2254 (voice)
    (508) 457-2310 (FAX)
    jbratton@usgs.gov

    Contact_Instructions:
    Current address: NOAA/GLERL 4840 S. State Rd. Ann Arbor MI 48108-9719 734-741-2235 John.Bratton@noaa.gov

Why was the data set created?

The purpose of this polyline shapefile is to indicate the ship's position during the continuous resistivity profile survey on May 16, 2007 in the Corsica River Estuary, Maryland. These lines can also be used to hyperlink to JPEG images of the corresponding resistivity profile enabling the resistivity data to be placed in spatial context with other GIS data.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    The continuous resistivity profile (CRP) system used on this cruise was an AGI SuperSting marine system described at the website: www.agiusa.com/marinesystem.shtml. The particular system used for this acquisition was a 50-m streamer with an 11 electrode array with electrodes spaced 5 meters apart. The source electrodes are graphite, while the receiver electrodes are stainless steel. A dipole-dipole configuration was used for the data collection in which two fixed current electrodes are assigned with the measurement of voltage potential between electrode pairs in the remaining electrodes. The maximum depth below the water surface the streamer can reach is approximately ¼ the streamer length. So for the 50-m streamer, maximum depth is about 12.5 meters. Each line of data acquisition records several files. The two files necessary for processing are the *.stg and the *.gps file. The STG file contains the resistivity data, while the GPS file contains the navigation information. The navigation system used in concert with the CRP system is a Lowrance LMS-480M with an LGC-2000 GPS antenna and a 200 kHz fathometer transducer. The transducer also contains a temperature sensor. Lowrance indicates the speed of sound used by the system is 4800 feet/second. Both the temperature and depth information are recorded in the logged GPS file. There are instances where no depth or temperature information is recorded due to an equipment problem. The CRP system images the subsurface electrical properties of an estuarine, riverine or lacustrine environment. Resistivity differences can be attributed to subsurface geology (conductive vs less conductive layers) and hydrogeologic conditions with fresh water exhibiting high resistivity and saline conditions showing low resistivity.

  2. How were the data generated, processed, and modified?

    Date: Nov-2009 (process 1 of 3)
    In ArcMap 9.2 an ArcMap extension written in Woods Hole (VACExtras, v2.1) was used to convert the individual navigation points to lines. The "Points to Line v2" tool within the extension was used. The user selects an attribute to be the unique identifier used to group the points into a line; in this case, the attribute "linename" was used. The script assumes the order of the points in the point shapefile is the order they need to be added to the line, and the projection of the output shapefile is the same as the input point shapefile. The user can also select additional attributes to be carried over to the output polyline shapefile. The value written out is the first occurrence of the attribute on the unique "line". The additional attributes carried over were gpstime, depth_m, jday, and gpsdate. This process step, along with all subsequent process steps, was performed by the same person: VeeAnn A. Cross.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

    Data sources used in this process:
    • resgpspnts_jd136.shp

    Data sources produced in this process:

    • resgpslns_jd136.shp

    Date: Apr-2010 (process 2 of 3)
    In ArcMap 9.2, XTools Pro (v. 5.2) was used to add the line length attribute "len_utm18". In XToolsPro - Table Operations - Calculate Area, Perimeter, Length, Acres and Hectares. Specified the output projection as NAD_1983_UTM_Zone_18N and set the output units as meters. Set the output field name to len_utm18.

    Data sources used in this process:

    • resgpslns_jd136.shp

    Data sources produced in this process:

    • resgpslns_jd136.shp

    Date: Jun-2010 (process 3 of 3)
    Two text attributes were added to the attribute table in ArcMap 9.2. The attribute "hotlink" will allow the user to hyperlink to the MATLAB JPEG images of the CRP line from within ArcMap. The attribute "hlink2" will allow the user to hyperlink to the EarthImager JPEG image of the long version of the CRP line from within ArcMap. See the entity and attribute overview for instructions on how to implement this feature. The links to L24F1, L24F2, L25F1, L26F1, L27F1_part1, L27F1_part2 and L28F1 profile data point to the modified files in which additional bathymetry data was used to supplement the missing bathymetry from the originally acquired CRP lines.

    Data sources used in this process:

    • resgpslns_jd136.shp

    Data sources produced in this process:

    • resgpslns_jd136.shp

  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

    The navigation system used was a Lowrance 480M with an LGC-2000 Global Positioning System (GPS) antenna. The antenna was located at the anchor point for the resistivity streamer, which is also directly above the fathometer transducer mount point. The GPS system is published to be accurate to within 10 meters.

  3. How accurate are the heights or depths?

    All collected bathymetry values were collected by the 200 kHz Lowrance fathometer. The fathometer was mounted starboard side aft, directly below the GPS antenna and the resistivity streamer tow point. The Lowrance manufacturer indicates the speed of sound used by the system to convert to depths is 4800 feet/second. All values are assumed to be accurate to within 1 meter.

  4. Where are the gaps in the data? What is missing?

    All the points in the input shapefile were used to generate these polylines. These lines represent all the survey lines from this day.

  5. How consistent are the relationships among the observations, including topology?

    Each line was generated in the same manner. The "hyperlink" files point to profiles with valid bathymetry data. For L24F1, L24F2, L25F1, L26F1, L27F1_part1, L27F1_part2 and L28F1 this means the hyperlinks point to the modified processed data in which bathymetry was derived from supplemental sources as the original data acquisition did not have bathymetry.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None.
Use_Constraints:
The public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.

  1. Who distributes the data set? (Distributor 1 of 1)

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Neither the U.S. government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    This WinZip file contains data available in ESRI polyline shapefile format. The user must have software capable of uncompressing the WinZip file and reading/displaying the shapefile.

Who wrote the metadata?

Dates:
Last modified: 07-Mar-2011
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
Woods Hole, MA 02543-1598

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.6 on Mon Mar 07 13:05:40 2011